Drier safety control



Dec. 4, 1951 Filed May les, 195o F'. L. BUTLER DRIER SAFETY CONTROL 2 SHEETS-SHEET l O Q 9 Q "s o l] zf A f /6 IS` i' l Inventor:

Dec. 4, 1951 F. L.. BUTLER DRIER SAFETY CONTROL 2' SHEETS-SHEET 2 Filed May 16 1950 PLQ. 5.

ITM/er1 tort Fhemk L Bpltler,

I-HS Att Ohne-,y

Patented Dec. 4, 1951 DBIER SAFETY CONTROL Frank L. Butler, Amcricus,

eral Electric Company,

York

Ga., assigner to Gena corporation of New Application May 18, 1950, Serial N0. 162,317

l 2 Claims.

This invention relates to a clothes drier oi' the type used in domestic laundries, and more particularly to a control device to prevent overheating in a clothes drier.

In motor driven clothes driers, the clothes are ordinarily tumbled about in a drum which rotates in a heated atmosphere. 'I'he conventional means for raising the air temperature within the casing accommodating the drier is by electrically energized or controlled heater means disposed in a duct system through, which air iiow is eniorced by a motor driven fan or the like. Said duct system may discharge into the room in which the drier is located and it is usual to employ a screen or other trap to prevent discharge 'of lint. Said trap will, after continuous use, collect enough lint to impede the free ilow of air through the duct system. Driers conventionally employ a thermostat to disconnect the power source when the temperature within the drier rises above a predetermined level. Should the thermostat fail to operate, as is often the case, the air temperature in the casing might build up dangerously, and abnormal turbulence resulting from faulty air circulation may allow some lint to settle on the heater and ultimately ignite.

The principal object of this invention is to provide means for automatically disconnecting the power source from the drier whenever the quantity of air flowing through the drier drops below a predetermined minimum, thereby providing back-up protection for the thermostat.

Another object of this invention is to provide means which will serve to remind the operator of the drier that the lint collecting screen should be cleaned periodically.

A further object of this invention is to provide means to disconnect the power source from the drier if a stalling load should be applied to the drive motor.

In the attainment of the foregoing objects, an important feature of this invention lies in an airpressure-sensitive switch, electrically operated switching means eiective to control the power input to the drier, and a lint collecting screen. The air-pressure-sensitive switch is so adjusted that whenever the air ow through said screen is below a predetermined level, the air switch will be closed, and said electrically operated switching means will be energized, thereby opening the power circuit to the drier.

For a better understanding of this invention, attention is now directed to the following description and the accompanying drawing and also to the appended claims in which the features of the invention believed to be novel are particularly pointed out. Fig. 1 is a side section elevation o! a typical drier utilizing this invention; Fig. 2 is a side elevation of the lint detector with the contacts open; Fig. 3 is a rear elevation of the lint detector with the contacts open; Fig. 4 is a side elevation of the lint detector with the contacts closed; and Fig. 5 is a typical drier control circuit utilizing this invention.

Referring to Fig. 1, the insulated casing I of the drier 2 has entrance louvers 3 and exit louvers 4 to permit passage of air through drier 2. An electrically energized heating means 5 is disposed near entrance louvers 3. Casing I also has a door 6 in the front thereof through which wet clothes may be passed into the foraminated tumbler 1. Tumbler 'I is mounted upon shaft 8 which is suitably journalled in bearings provided in the rear wall of casing I, shaft 8 being connected to a drive motor 9 by a speed reduction means such as a system of belts and sheaves or the like. An impeller fan I0 is directly connected to the motor S by a shaft II. The fan I0 is positioned at the opening of a pressure compartment IIa which substantially encloses the motor 9 and has in its upper edge near the casing a slot (not shown). The air within the compartment IIa is pressurized by the fan I0 and escapes through the slotted opening in the form of a sheet along the sides of the casing, passing across the heater 5 and filtering into the foraminous drum 'I. This construction is more fully disclosed in the copending application of John H. Robinson and Paul L. Paulson for Laundry Dryer, Serial No. 209,280, iiled February 3, 1951, and assigned to the General Electric Coirpany, assignee of the present application. A suitable duct system I2 is provided to channel the humid lint-bearing air from the tumbler I through a removablelintcatching screen I3 and through exit louvers 1. Trackways I4 are provided in duct I2 to serve as guides for screen I3. An air-pressure-sensitive switching mechanism I5 is disposed in duct I2 between screen I3 and exit louvers l.

Referring to Fig. 2 and Fig. 3, air-pressuresensitive switch I5 consists of a vane I6 mounted on a pivot I'I in duct I2. Mounted on the lower end of vane I6 is a contact I8 cooperating with the contacts I9 mounted on the bottom of duct I2. Contacts IB also serve as a stop for vane I6 when it tends to move in a clockwise direction. An adjustable weight 20 mounted on the upper end of vane IB partially balances the torque due to contact I8 when vane I6 is in a horizontal position, and it adds to the torque due to contact I8 when vane I6 is in a vertical position or slight- 1y turned in the contact-opening direction. 'I'he stop bar 2|. prevents vane I8 irom being turned 'too far in the contact-opening direction. .Refer-` ring to Fig. 5, a source of electric power is connected to drier 2 through the supply conductors 22. Supply conductors 22 are connected to drier 2 by depressing the push button switch 23 which energizes the relay 24 closing the normally open contacts 25 and 26. 'I'he timer 21 is adjusted by the operator tol disconnect motor 9 and heater 5 after a desired period oi' operation. The thermostat 28 is adjusted to disconnect motor 9 and heater 5 if the temperature inside the drier rises above a predetermined level. The door switch 29 disconnects motor 9 and heater 5 any time door 6 is opened. A centrifugal switch 30 removes the motor starting iield windings 3| from the circuit and switches the relay 32 into the circuit when motor 9 comes up to a predetermined operating speed. When relay 32 is energized, it closes the normally open contacts 33 and 34 connecting lint detector I5 to the relay 35, and connecting heater means 5 to the power source respectively.'

When relay 35 is energized the normally closed contacts 36 and 31 are opened, thereby disconnecting heater means 5 and motor 9 from supply conductors 22.

When push button switch23 is depressed, relay 24 is energized thereby closing normally open contacts 25 and 26 and connecting motor 9 to the power source if door switch 29 is closed. At this time centrifugal switch 30 is in the starting position. When motor 9 comes up to the predetermined operating speed, centrifugal switch 30 disconnects the starting winding 3i and connects relay 32, thereby closing normally open contacts 33 and 34 and connecting relay 35 to lint detector I5 and heating means 5. Fan I 0 draws fresh air into drier 2 through entrance louvers 3. Said air passes over heating means 5 in the manner previously explained and through foraminated tumbler 1 where it acquires moisture and lint from the clothes therein. 'I'he humid, lintbearing air is then drawn downward into duct system I2 and forced through screen I3, airpressure-sensitive switch I5, and exit louvers 4 into the outer room. As long as the air flowing through air-pressure-sensitive switch I5 is above the predetermined level, vane I6 will be held in the horizontal position as shown in Fig. 2. When stalling load is applied to motor 9 or when screen I3 becomes obstructed so that the air flow through switch I5 falls below the predetermined minimum, vane I6 will gradually turn in the con- -tact-closing direction until counterweight 2l) passes over pivot I1 at which time vane I6 will move rapidly in the contact-closing direction until cooperating contacts I8 and I9 areA closed. When cooperating contacts I8 and I9 close, relay 35 is energized and normally closed contacts 36 and 31 are opened, de-energizing heating means 5 and relay 24 which in turn opens contacts 25 and 26 disconnecting the remaining drier circuit from the supply conductors 22. When centrifugal switch 39 turns to the starting position, relay 32 releases contacts 33 and 34. Drier 2 is now in its normal 'inoperative condition.

If the air iiow through screen I3 is below the predetermined level when relay 32 is energized, cooperating contacts I8 and I9 remain closed, contacts 33 are closed by relay 32 and supply conductors 22 are disconnected from the drier circuit as hereinbefore described.

While the present invention has been described by reference to particular elements thereof, it will be understood that this is by way of illustration of the principles involved and that tho skilled inthe may make many modifications in the arrangement and mode o! operation. Therefore, I contemplate by the appended claims to cover any such modications as fall within the true spirit and scope ,of this invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

' l1. In a clothes drieror the like, having a casing, a foraminated clothes receiving drum mounted for rotation in said casing, means inciuding an inlet passage and an outlet passage in said casing for permitting air circulation therethrough, a removable lint-collecting scree'n in said outlet passage to trap lint which may be suspended in said air ow.. electrically operated heater means within said casing for raising the air temperature therein, a motor for rotating said drum, a fan driven by said motor i'or discharging heated air from said casing at a predetermined rate, and circuits for respectively connecting said motor'and said heater energizing means to a source oi electrical energy, the improvement in electrical'control means for said circuits comprising a relay having normally open contacts in series in saidmotor circuit, a circuit I vfor energizing said relayto close said contacts, a

relay having normally open contacts in series in said heater energizing circuit, a circuit for energizing sad relay to close said contacts, a third relay having normally closed contacts respectively in the energizing circuit of said rst relay and in the said heater energizing circuit, means for connecting said last named relay to a source of electrical energy to open said normally closed contacts upon reduction in air flow through said screen, including fixed contacts and a movable contact in series in said third relay energizing circuit and a pivotally mounted vane carrying said movable contact and disposed downstream of said screen in the path oi discharging air flow to be rotated thereby to maintain an open circuit condition under normal air flow conditions, said vane being counterweighted to cause said last-named contacts to closelupon reduction in air ow throuvh said screen as aforesaid.

2. In a clothes drier or the like, having a casing. mounted for rotation in said casing, means including an inlet passage and an outlet passage in said casing for permitting air circulation therethrough, a removable lint screen in said outlet passage to trap lint which may be suspended in said air ow, electrically operated heater means within said casing for raising the air temperature therein, a motor for rotating said casing, a fan driven by said motor for discharging heated air from said casing at a predetermined rate, and circuits for respectively connecting said motor and said heater energizing means to a source of electrical energy, the improvement in electrical means for said circuits com: prising a relay having holding contacts and having normally open contacts in series in said motor circuit, a circuit for energizing said relay to close a foraminated clothes receiving drum contacts upon reduction in air fiow through said screen, including a xed contact and a movable contact in series in said third relay energizing circuit and a pivotaliy mounted vane carrying said movable contact and disposed downstream of said screen in the path of discharging air ow to be rotated thereby to maintain an open circuit condition under normal air ow conditions, said vane being counterweig'nted to cause said last-named contacts to close upon reduction in air iow through said screen as aforesaid.

FRANK L. BUTLER.

REFERENCES CITED The following references are of record in the le of this patent:

Number 6 UNITED STATES PATENTS Name Date Carroll June 26, 1928 Matcovich May 14, 1929 Gehnrich Mar. 10, 1931 Carraway Dec. 11, 1934 White Mar. 23, 1943 Vermilya Oct. 24, 1944 Davis Mar. 26, 1946 Morris Oct. 25, 1949 Gorsuch Apr. 25, 1950 

